A teenager battered a partygoer and left him permanently disfigured after a window was smashed at his Bonhill home.

Shaun McCarthy, 19, threw the man out of his Nobleston flat when he began to fight with another guest.

But, as he left, the disgruntled partygoer smashed the close window – and McCarthy then attacked him.

Last week McCarthy appeared at Dumbarton Sheriff Court and admitted repeatedly punching the man on the head and body to his injury and permanent disfigurement on January 15 this year.

The court heard that the victim had been among a group who had gone to McCarthy’s house after partying in a Balloch nightclub.

Fiscal depute John Service said: “While they were at the house it’s accepted that the atmosphere soured. An argument broke out between the accused and the complainer. This resulted in the complainer being asked to leave. He did so. However, on his way out there was damage caused by him to a window of the common close of the flat.”

McCarthy heard the sound of breaking glass and followed the man out into the street for a “square-go”.

Later, during a police interview McCarthy accepted that he punched the victim three times to the body and twice to the face, particularly around the cheek area where the main injuries were caused.

The man was taken to the Royal Alexandra Hospital in Paisley where 14 stitches were inserted to a head wound, four to the left side of his face, and 11 to a cut just under his eye which left him with a permanent scar.

Steven Wight, defending, said: “Effectively what happened is that the complainer and his friends latched on to a group making their way from the nightclub back to Mr McCarthy’s home. The complainer and his friend were aggressive and argumentative and were starting to fight with each other.

“They knocked into other items in the house and caused some damage and eventually he was put out. As he was leaving he then caused damage in the common close area. The red mist descended and together with the consumption of alcohol this led Mr McCarthy to go outside where this square-go took place.

“There was evidence of them rolling around the ground and punching each other. Effectively the loser was injured and police were contacted.

“He is a first offender in the true sense of the word. He has got a very good, strong , stable background. I can say with some considerable force that as far as Mr McCarthy is concerned this is a one-off.”

Sheriff Aisha Anwar told McCarthy: “You have committed a serious and violent assault. You pursued the complainer after he left your home.

“The act of punching anyone in the head is inherently dangerous.”

McCarthy was placed on a one-year community payback order and was ordered to carry out 200 hours unpaid work. He will also be supervised for the next six months and be tagged for two months.